I'm not 100% sure here so if someone knows better go with that. I feel its due to the smoothing groups that are present in the 3DS file. It appears that the stalks have them but the leaves do not. Export from Poser in OBJ format and then open that file in UVMapper. Go to Edit/Tools/Weld Vertices. Save the file with a new name. Now bring that into Poser to see if its improved.